/*
 * Copyright (c) 1997, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
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 *
 */

package java.awt.geom;

import java.util.*;

/**
 * A utility class to iterate over the path segments of an rounded rectangle
 * through the PathIterator interface.
 *
 * @author Jim Graham
 */
class RoundRectIterator implements PathIterator {

  double x, y, w, h, aw, ah;
  AffineTransform affine;
  int index;

  RoundRectIterator(RoundRectangle2D rr, AffineTransform at) {
    this.x = rr.getX();
    this.y = rr.getY();
    this.w = rr.getWidth();
    this.h = rr.getHeight();
    this.aw = Math.min(w, Math.abs(rr.getArcWidth()));
    this.ah = Math.min(h, Math.abs(rr.getArcHeight()));
    this.affine = at;
    if (aw < 0 || ah < 0) {
      // Don't draw anything...
      index = ctrlpts.length;
    }
  }

  /**
   * Return the winding rule for determining the insideness of the
   * path.
   *
   * @see #WIND_EVEN_ODD
   * @see #WIND_NON_ZERO
   */
  public int getWindingRule() {
    return WIND_NON_ZERO;
  }

  /**
   * Tests if there are more points to read.
   *
   * @return true if there are more points to read
   */
  public boolean isDone() {
    return index >= ctrlpts.length;
  }

  /**
   * Moves the iterator to the next segment of the path forwards
   * along the primary direction of traversal as long as there are
   * more points in that direction.
   */
  public void next() {
    index++;
  }

  private static final double angle = Math.PI / 4.0;
  private static final double a = 1.0 - Math.cos(angle);
  private static final double b = Math.tan(angle);
  private static final double c = Math.sqrt(1.0 + b * b) - 1 + a;
  private static final double cv = 4.0 / 3.0 * a * b / c;
  private static final double acv = (1.0 - cv) / 2.0;

  // For each array:
  //     4 values for each point {v0, v1, v2, v3}:
  //         point = (x + v0 * w + v1 * arcWidth,
  //                  y + v2 * h + v3 * arcHeight);
  private static double ctrlpts[][] = {
      {0.0, 0.0, 0.0, 0.5},
      {0.0, 0.0, 1.0, -0.5},
      {0.0, 0.0, 1.0, -acv,
          0.0, acv, 1.0, 0.0,
          0.0, 0.5, 1.0, 0.0},
      {1.0, -0.5, 1.0, 0.0},
      {1.0, -acv, 1.0, 0.0,
          1.0, 0.0, 1.0, -acv,
          1.0, 0.0, 1.0, -0.5},
      {1.0, 0.0, 0.0, 0.5},
      {1.0, 0.0, 0.0, acv,
          1.0, -acv, 0.0, 0.0,
          1.0, -0.5, 0.0, 0.0},
      {0.0, 0.5, 0.0, 0.0},
      {0.0, acv, 0.0, 0.0,
          0.0, 0.0, 0.0, acv,
          0.0, 0.0, 0.0, 0.5},
      {},
  };
  private static int types[] = {
      SEG_MOVETO,
      SEG_LINETO, SEG_CUBICTO,
      SEG_LINETO, SEG_CUBICTO,
      SEG_LINETO, SEG_CUBICTO,
      SEG_LINETO, SEG_CUBICTO,
      SEG_CLOSE,
  };

  /**
   * Returns the coordinates and type of the current path segment in
   * the iteration.
   * The return value is the path segment type:
   * SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE.
   * A float array of length 6 must be passed in and may be used to
   * store the coordinates of the point(s).
   * Each point is stored as a pair of float x,y coordinates.
   * SEG_MOVETO and SEG_LINETO types will return one point,
   * SEG_QUADTO will return two points,
   * SEG_CUBICTO will return 3 points
   * and SEG_CLOSE will not return any points.
   *
   * @see #SEG_MOVETO
   * @see #SEG_LINETO
   * @see #SEG_QUADTO
   * @see #SEG_CUBICTO
   * @see #SEG_CLOSE
   */
  public int currentSegment(float[] coords) {
    if (isDone()) {
      throw new NoSuchElementException("roundrect iterator out of bounds");
    }
    double ctrls[] = ctrlpts[index];
    int nc = 0;
    for (int i = 0; i < ctrls.length; i += 4) {
      coords[nc++] = (float) (x + ctrls[i + 0] * w + ctrls[i + 1] * aw);
      coords[nc++] = (float) (y + ctrls[i + 2] * h + ctrls[i + 3] * ah);
    }
    if (affine != null) {
      affine.transform(coords, 0, coords, 0, nc / 2);
    }
    return types[index];
  }

  /**
   * Returns the coordinates and type of the current path segment in
   * the iteration.
   * The return value is the path segment type:
   * SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE.
   * A double array of length 6 must be passed in and may be used to
   * store the coordinates of the point(s).
   * Each point is stored as a pair of double x,y coordinates.
   * SEG_MOVETO and SEG_LINETO types will return one point,
   * SEG_QUADTO will return two points,
   * SEG_CUBICTO will return 3 points
   * and SEG_CLOSE will not return any points.
   *
   * @see #SEG_MOVETO
   * @see #SEG_LINETO
   * @see #SEG_QUADTO
   * @see #SEG_CUBICTO
   * @see #SEG_CLOSE
   */
  public int currentSegment(double[] coords) {
    if (isDone()) {
      throw new NoSuchElementException("roundrect iterator out of bounds");
    }
    double ctrls[] = ctrlpts[index];
    int nc = 0;
    for (int i = 0; i < ctrls.length; i += 4) {
      coords[nc++] = (x + ctrls[i + 0] * w + ctrls[i + 1] * aw);
      coords[nc++] = (y + ctrls[i + 2] * h + ctrls[i + 3] * ah);
    }
    if (affine != null) {
      affine.transform(coords, 0, coords, 0, nc / 2);
    }
    return types[index];
  }
}
